Uveitis is defined as inflammation of the uveal tract—the iris, ciliary body, and choroid. However, the retina and fluid within the anterior chamber and vitreous are often involved as well. About half of cases are idiopathic; identifiable causes include trauma, infection, and systemic diseases, many of which are autoimmune. Symptoms include decreased vision, ocular ache, redness, photophobia, and floaters. Although uveitis is identified clinically, identifying the cause typically requires testing. Treatment depends on cause, but typically includes topical, locally injected, or systemic corticosteroids with a topical cycloplegic-mydriatic drug. Noncorticosteroid immunosuppressive drugs may be used in severe and refractory cases.
Uveitis is inflammation of the uveal tract (see figure Cross-section of the eye). Uveitis is classified anatomically as
Anterior uveitis: Localized primarily to the anterior segment of the eye, includes iritis (inflammation in the anterior chamber alone) and iridocyclitis (inflammation in the anterior chamber and anterior vitreous)
Intermediate uveitis: Localized to the vitreous cavity and/or pars plana (part of the ciliary body that extends posteriorly beyond the junction of the iris and sclera)
Posterior uveitis: Any form of retinitis, choroiditis, or inflammation of the optic disk
Panuveitis: Inflammation involving anterior, intermediate, and posterior structures
Uveitis is also classified by onset (sudden or insidious), duration (limited or persistent), and course (acute, recurrent, or chronic).
Cross-section of the eye
The zonules of Zinn keep the lens suspended, and the muscles of the ciliary body focus the lens. The ciliary body also secretes aqueous humor, which fills the anterior and posterior chambers, passes through the pupil into the anterior chamber, and drains primarily via the Schlemm canal. The iris regulates the amount of light entering the eye by adjusting the size of its central opening, the pupil. Visual images are focused on the retina. The conjunctiva covers the eyeball and lines the upper and lower eyelids; it ends at the limbus. The cornea is covered with epithelium that is more sensitive than and differs from the conjunctival epithelium. |
Etiology of Uveitis
Causes of anterior uveitis include
Idiopathic or postsurgical (most common cause)
Trauma
Herpesvirus infection (herpes simplex virus [HSV], varicella-zoster virus [VZV], and cytomegalovirus [CMV])
Tubulointerstitial nephritis and uveitis (TINU)
Causes of intermediate uveitis include
Idiopathic (most common)
Tuberculosis (TB)
Lyme disease (in endemic regions)
Causes of posterior uveitis (retinitis) include
Idiopathic (most common)
CMV (in immunocompromised patients)
Causes of panuveitis include
Idiopathic (most common)
Symptoms and Signs of Uveitis
Symptoms and signs may be subtle and vary depending on the site and severity of inflammation.
Anterior uveitis tends to be the most symptomatic (especially when acute), usually manifesting with
Pain (ocular ache)
Redness
Photophobia
Decreased vision (to a variable degree)
Chronic anterior uveitis may have less dramatic symptoms and present with irritation or decreased vision.
Signs include hyperemia of the conjunctiva adjacent to the cornea (ciliary flush or limbal injection). Slit-lamp findings include keratic precipitates (white blood cell clumps on the inner corneal surface), cells and flare (a haze) in the anterior chamber (aqueous humor), and posterior synechiae. With severe anterior uveitis, white blood cells may layer in the anterior chamber (hypopyon).
Image courtesy of Sunir Garg, MD.
Intermediate uveitis is typically painless and manifests with
Floaters
Decreased vision
The primary sign is cells in the vitreous humor. Aggregates and condensations of inflammatory cells often occur, appearing as "snowballs." Vision may be decreased because of floaters or cystoid macular edema, which results from fluid leakage from blood vessels in the macula. Confluent and condensed vitreous cells and snowballs over the pars plana (part of the ciliary body that extends posteriorly beyond the junction of the iris and sclera) may cause a classic "snowbank" appearance, which can be associated with neovascularization of the retinal periphery.
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Posterior uveitis may give rise to diverse symptoms but most commonly causes floaters and decreased vision as occurs in intermediate uveitis. Signs include
Cells in the vitreous humor
White or yellow-white lesions in the retina (retinitis), underlying choroid (choroiditis), or both
Retinal vasculitis (with whitening or obliteration of blood vessels)
Optic disk edema
Panuveitis may cause any combination of the previously mentioned symptoms and signs.
Complications
Serious complications of uveitis include profound and irreversible vision loss, especially when uveitis is unrecognized, inadequately treated, or both.
The most frequent complications include
Cataract (secondary to the disease process and/or to corticosteroid treatment)
Cystoid macular edema (the most common cause of decreased vision in patients with uveitis)
Glaucoma (secondary to the disease process and/or to corticosteroid treatment)
Band keratopathy (calcium deposition in a band-like pattern across the cornea)
Neovascularization of the retina, optic nerve, or iris
Hypotony (an intraocular pressure that is too low to support the health of the eye)
Diagnosis of Uveitis
Slit-lamp examination
Ophthalmoscopy after pupil dilation
Uveitis should be suspected in any patient who has ocular ache, redness, photophobia, new onset or changing floaters, or decreased vision. Patients with unilateral anterior uveitis have ocular ache in the affected eye if light is shined in the unaffected eye (true photophobia), which is uncommon in conjunctivitis.
Diagnosis of anterior uveitis is by recognizing cells and flare in the anterior chamber. Cells and flare are seen with a slit lamp and are most evident when using a narrow, intensely bright light focused on the anterior chamber in a dark room. Findings of intermediate and posterior uveitis are most easily seen after dilating the pupil. Indirect ophthalmoscopy (usually done by an ophthalmologist) is more sensitive than direct ophthalmoscopy. (NOTE: If uveitis is suspected, patients should be referred immediately for complete ophthalmologic evaluation.)
Many conditions that cause intraocular inflammation can mimic uveitis and should be considered in the appropriate clinical settings. Such conditions include severe conjunctivitis (eg, epidemic keratoconjunctivitis), severe keratitis (eg, herpetic keratoconjunctivitis, peripheral ulcerative keratitis), and severe scleritis.
Acute angle-closure glaucoma can cause redness and severe pain similar to that of uveitis, which is why it is important to check intraocular pressure at every visit. Uveitis is often (but not always) associated with a low intraocular pressure, whereas pressure is typically high in acute angle-closure glaucoma. Uveitis also can be distinguished from angle-closure glaucoma by the absence of corneal haze and the presence of a deeper anterior chamber.
Other masqueraders include intraocular cancers in the very young (typically retinoblastoma and leukemia) and in older people (intraocular lymphoma). Much less commonly, retinitis pigmentosa can manifest with mild inflammation, which may be confused with uveitis.
Treatment of Uveitis
Corticosteroids (usually topical) and sometimes other immunosuppressive drugs
Cycloplegic-mydriatic drugs
Sometimes antimicrobial drugs
Sometimes surgical therapy
Particularly severe or chronic cases may require systemic corticosteroids or systemic noncorticosteroid immunosuppressive drugs. For example,
Additional treatment for severe or chronic cases may require laser phototherapy, cryotherapy applied transsclerally to the retinal periphery, or surgical removal of the vitreous (vitrectomy) (1–3).
Treatment references
1. Jaffe GJ, Dick AD, Brézin AP, et alN Engl J Med 8;375(10):932-43, 2016. doi: 10.1056/NEJMoa1509852
2. Lee J, Koreishi AF, Zumpf KB, et alOphthalmology S0161-6420(20)30333-X, 2020. doi: 10.1016/j.ophtha.2020.04.009
3. Kruh JN, Yang P, Suelves AM, et alOphthalmology 121(1):358-364, 2014. doi: 10.1016/j.ophtha.2013.07.019
Key Points
Inflammation of the uveal tract (uveitis) can affect the anterior segment (including the iris), intermediate uveal tract (including the vitreous), or posterior uvea (including the choroid, retina, and optic nerve).
Most cases are idiopathic, but known causes include infections, trauma, and autoimmune disorders.
Findings in acute anterior uveitis include aching eye pain, true photophobia, redness closely surrounding the cornea (ciliary flush), and, on slit-lamp examination, cells and flare.
Chronic anterior uveitis may have less dramatic symptoms and present with eye irritation or decreased vision.
Intermediate and posterior uveitis tend to cause less pain and eye redness but more floaters and decreased vision.
Diagnosis is confirmed by slit-lamp examination and ophthalmoscopic examination (often indirect) after pupillary dilation.
Treatment should be managed by an ophthalmologist and often includes corticosteroids and a cycloplegic-mydriatic drug along with treatment of any specific cause.
